Update app.py

app.py

@@ -564,7 +564,8 @@ Example for 1 content slide:
         
         # Generate PDF from slides
         pdf_file = generate_slides_pdf(slides)
-        pdf_path = f"{OUTPUT_DIR/pdf_file}"
+        pdf_path = os.path.join(OUTPUT_DIR, pdf_file)
+        print(f"PDF file generated: {pdf_file}")
         
         audio_files = []
         speaker_audio = speaker_audio if speaker_audio else "feynman.mp3"